Bad Gas Sucks *Weak Rant*

NutBucket

Lifer
Aug 30, 2000
27,152
635
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After a week of checking out one of our WRXs trying to find a boost leak and/or broken part, it seems the trouble all along was a bad tank of gas causing the ECU to cut boost (7psi max, spring pressure of the wastegate actuator) and some detonation under load.

I should have looked at this possibility first as the simplest explanation is usually right. But, I was fooled because we filled our other WRX at the same station the following day and experience no driveability issues. I guess that's the difference between being modified and stock.

Anyway, since my weak rant is weak, I'll just complain that after filling about 2/3 of a tank with real 91, the car definitely drives better but still isn't hitting full boost and is still pinging a bit. Hopefully another tank of 91 will bring things back to normal.
 

ThatsABigOne

Diamond Member
Nov 8, 2010
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There is bad gas? Or you just filled the car with lower octane?

Lower octane != Bad gas.
 
Sep 7, 2009
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In my opinion 'bad gas' is bad enough to make the engine run differently. Sometimes it's water in the tank (either leaking from the top or condensation, and other times I swear it's not 100% premium.

I've also heard about people having fuel pump issues after filling up when the tanker has just refilled the station's tanks, as sediment gets mixed up from the bottom.



And yes, bad gas sucks. Does anyone have firsthand experience with damaged engines due to bad gas? I wonder how the station would handle it if you showed up with a receipt for a repair bill after getting gas from them.
 

ThatsABigOne

Diamond Member
Nov 8, 2010
4,422
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I do not think the sediment would be a huge issue. That is what we got fuel filters for. And they are extremely easy to change.

It is just people's minds performing differently.
 

NutBucket

Lifer
Aug 30, 2000
27,152
635
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And yes, bad gas sucks. Does anyone have firsthand experience with damaged engines due to bad gas? I wonder how the station would handle it if you showed up with a receipt for a repair bill after getting gas from them.
Good luck with that...unless the engine is running at the ragged edge and blows up within a few days of said fill up. Even then, almost impossible to prove where the gas came from.
 

Raizinman

Platinum Member
Sep 7, 2007
2,355
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meettomy.site
It’s very common around this time of the year to get bad gas. The reason is:

The convenience store needs extra money for holiday pay and end of year bonuses - thus putting regular gas in the premium tank to make extra profit.

Likewise:

The customers need extra money for holiday presents/gifts - thus purchasing regular gas instead of the premium their car needs. This also causes the premium tank gasoline to get old as nobody is buying it.

Bottom line: The gas in the premium tank is either regular or old, or both. Not a good time of the year to purchase premium gas. Instead, purchase regular gas and get aftermarket octane booster.
 

NutBucket

Lifer
Aug 30, 2000
27,152
635
126
Trouble is, it take A LOT of octane booster to get from 87 --> 91. Here in LA, there are plenty of cars running around that require premium so I doubt the gas is old.

As for the station knowingly filling regular in the premium tank...could happen. Might explain why that station is so cheap :p But you wouldn't expect that from a Chevron Station.
 

Ben90

Platinum Member
Jun 14, 2009
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And yes, bad gas sucks. Does anyone have firsthand experience with damaged engines due to bad gas? I wonder how the station would handle it if you showed up with a receipt for a repair bill after getting gas from them.
Good luck with that...unless the engine is running at the ragged edge and blows up within a few days of said fill up. Even then, almost impossible to prove where the gas came from.
QuikTrip
 

disappoint

Lifer
Dec 7, 2009
10,132
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wine.jpg
 

SabaII

Member
Dec 16, 2011
127
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I got some bad gas up north once. Filled up and I could just smell it was bad. On my 350mile trip back home I noticed a 1.5-2 mpg drop in fuel economy. Put some treatment in and fresh gas from my regular station and the economy picked back up. Oh and up here its Kwik Trip!
 

exdeath

Lifer
Jan 29, 2004
13,679
10
81
One night even though I picked 91, I noticed half way through that it was on 87. Longest half tank of gas in my life.

Can't take chances at 17 psi on pump gas and fine tuned on a dyno within a couple degrees timing from knock.
 

disappoint

Lifer
Dec 7, 2009
10,132
382
126
One night even though I picked 91, I noticed half way through that it was on 87. Longest half tank of gas in my life.

Can't take chances at 17 psi on pump gas and fine tuned on a dyno within a couple degrees timing from knock.

Why didn't you grab a bottle of octane boost?
 

kamikazekyle

Senior member
Feb 23, 2007
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Supposedly someone over on the CBR250.net forums had so much water in his gas after a fillup he blew the engine. Not completley kaboom, but needing a full teardown. My business law professor in college got a watered down tank once from a station, but it didn't actually damage her engine.

I've never had bad gas myself, though all my vehicles until now would go fine on 87 and I never noticed any issues. I did notice some roughness on my new Multistrada at low speeds and it did stall twice at higher temps, but I think that might have been the marine Stabil I put in. Supposedly it screws with the octane rating and the Multi has a 20% increase in comrpession ratio as well as a dyno tuned custom ECU, so I'm thinking that might be the cause. I'm working on burning through the tank and trying to get my engine temps up again to be sure before I start digging into other things.

Speaking of which, anyone use/try those ethanol treatment additives? The ones that you're supposed to use every fill up, not the winterizing/storage ones. I'm curious as to how that would affect E10 gas. I'm thinking -- in the case of the Stabil branded version -- it's nothing more than the non-marine version of Stabil with a non-alcohol based octane booster and some detergents. My Googling has resulted in stuff ranging from snake oil to nectar of the gods without much in the way of actual reviews.
 

NutBucket

Lifer
Aug 30, 2000
27,152
635
126
I did some reading up on octane booster. Seems they typically claim something like "up to 10 point boost" or something similar. The catch is, each point is 0.1 and the "up to" verbiage. Sounds a lot like snake oil to me.
 

exdeath

Lifer
Jan 29, 2004
13,679
10
81
I did some reading up on octane booster. Seems they typically claim something like "up to 10 point boost" or something similar. The catch is, each point is 0.1 and the "up to" verbiage. Sounds a lot like snake oil to me.

Torco is the only one I would use but it's not readily available.
 

kamikazekyle

Senior member
Feb 23, 2007
538
0
0
I did some reading up on octane booster. Seems they typically claim something like "up to 10 point boost" or something similar. The catch is, each point is 0.1 and the "up to" verbiage. Sounds a lot like snake oil to me.

I read the same thing about the octane boost claims on OB additives when I was trying to find stuff on ethanol countering additives. I did happen to come across a website that listed the contents/chemicals used in a lot of different additives, and a bunch of the octane boosters and cleansers use alcohol of some sort. When you combine the alcohol based octane booster with ethanol modified gas it ups the alcohol content and just makes things worse.

I might see about giving the Star Brite and Stabil regular use ethanol treatments a try and see how it affects performance/mileage. Push comes to shove I need a bit of a stabilizer for my car anyway since it can be up to two months before I have to fill it up with gas.
 

NutBucket

Lifer
Aug 30, 2000
27,152
635
126
New development: I either have a fouled plug or a dead coil pack as the car decided to idle on 3 cylinders tonight and the exhaust smelled of gas. Will investigate tomorrow.